A cell surface receptor for the extracellular matrix glucoprotein laminin has been demonstrated via several methods in our laboratory. The proposed study is designed to biochemically characterize the receptor for laminin with regard to its location in the membrane and behavior after ligand binding. We have measured the number of receptors via live cell binding techniques to be 80-110,000 receptors per cell using various cell types (ie. human pancreatic carcinoma, breast carcinoma and bladder carcinoma). The major questions addressed by this study are a) Does the laminin receptor undergo internalization after ligand binding? b) Does the ligand (a part of whole) enter the cell? c) What endocytosis pathway is used by the cell? d) Is the receptor recycled? These questions will be addressed using temperatures binding curves, immunoelectron microscopy (employing antibodies to laminin or to the receptor) or pharmacologic agents which block endocytosis.